Families search for missing as death toll rises in Brazilian floods

Bodies are strewn among fallen boulders and abandoned belongings there

A government minister says "environmental irresponsibility" caused the tragedy

The city of Nova Friburgo is the hardest hit, with 335 deaths reported

Rio De Janeiro (CNN) -- The death toll from devastating flooding in Brazil continued to climb Tuesday, surpassing 700, the government said.

A helicopter rescued 18 people from a city in Brazil's Rio de Janeiro state after rains caused devastating flooding and mudslides in the mountainous region.

Four children -- including a 30-day-old baby, were among those lifted to safety Monday. The Air Force said one of them -- 6-year-old Guilherme Carvalho -- summed up the feelings of the group with a simple exclamation: "Relief!"

But rescuers have not been able to reach some hard-hit areas, and many more people are feared dead. Forecasters predict rain will continue for several days in areas already submerged in water.

The death toll from flooding in Rio de Janeiro state has climbed to 710, according to government figures released Tuesday. And thousands are homeless across the state.

Other states in the South American country have also seen heavy rainfall. Last week, authorities in neighboring Sao Paulo state said 24 people had been killed by flooding.

In Rio de Janeiro state, flooding and mudslides turned the once-picturesque tourist town of Teresopolis into a wasteland. Bodies and belongings remained strewn amongst fallen boulders Monday as family members searched for loved ones in the rubble.

Outside a makeshift morgue in Teresopolis -- where the government said at least 292 people had died in flooding -- a crowd of people waited for their turn to identify loved ones.

Marco Antonio Siqueira Costa said the last time he saw his brother, sister-in-law and niece was a few days ago, before mud buried their house.

"I think that last meeting was God's way of granting us a farewell," he said.

Residents in the city donned masks and helped clean streets or deliver first aid. Others combed the city searching desperately for missing loved ones.

Meanwhile, experts and officials tried to pinpoint what caused the catastrophe.

"Combine a weather event and environmental irresponsibility and the sum equals a tragedy," said Carlos Minc, Rio de Janeiro's environment minister.

Minc said he wants to stop construction of homes in high-risk areas, such as river banks or steep mountain slopes -- a practice that he said was encouraged by previous governments. He pointed to Nova Friburgo -- the hardest-hit city, according to government figures, which list 335 deaths due to flooding there.

"We are monitoring river levels, but it isn't enough. In Nova Friburgo, for example, we had warned six hours in advance that the river was overflowing, but...there is no emergency plan or drills with the population so they know what to do in a situation like this," he said.

Brazilian authorities have been criticized for a lack of disaster planning, and for allowing people to build homes in areas known to become treacherous in the rainy season.

They are under increasing pressure to show a strong response. Brazil is scheduled to host the World Cup in 2014 and the Olympics in 2016.

CNN's Helena de Moura, Fabiana Frayssinet and Nelson Quinones contributed to this report.